Nutrition for Horses With Liver Damage
The liver is the largest gland in a horse’s body and is responsible for over 100 different bodily functions, many of them to do with digestion and processing of nutrients. When the liver sustains damage, for example through ragwort poisoning, this will have extensive consequences for the horse’s health. Animals with such afflictions need extra support, which can be given amongst others by adapting their diets. In this bulletin, the nutritional experts from Saracen offer a few practical tips to optimise the diet of a horse with liver damage.
If you have any questions or are looking for tailored nutritional advice for your horse with liver damage, contact nutritional expert Lizzie Drury from Saracen Horse Feeds via Animal Royal.
Liver damage is untreatable, but an adapted diet can bring relief.
A simple organ with complex functionality
Depending on the size of the horse, their liver weighs between 5 and 9 kilograms. It is situated right behind the diaphragm and in front of the stomach, where it is held in place by six ligaments and the pressure of the surrounding organs. Within the metabolic system, the liver is assisted by two other important glands: the salivary gland and the pancreas.
At the cellular level, the liver is a fairly simple organ: it consists only of various identical cells called hepatocytes. These cells are continually metabolically active. This comes as no surprise, given that over 100 different functions are currently ascribed to the liver. These can be divided into five categories:
Digestive and secretory function
In a horse’s body, the liver produces bile, which is necessary for fat digestion and neutralisation of the contents of the small intestine. Horses have no gall bladder, and the bile duct is wide to compensate for this. Bile is therefore continually produced in a diluted form and carried through the liver via the bile duct, which branches through the liver tissues. It carries not only bile, but also transports various waste products from the metabolic system, including hormones and enzymes.
Metabolic function (carbohydrates, proteins and fat metabolism)
The liver is the body’s main store of utilisable energy. After a meal has been eaten, glucose is absorbed and stored as glycogen in the liver and muscles. When blood glucose drops, glycogen is excreted. When blood glucose rises, glycogen is absorbed. This process is mediated by several hormones, including insulin.
The liver is also involved in the metabolism of lipids. When the horse is using its fat stores as a major energy source, for example in the case of starvation or when energy requirements exceed energy intake, large amounts of fat appear in the liver. Accumulation of fat in the liver is a sign of rapid fat mobilisation in preparation for the horse’s metabolism to provide energy.
Lastly, the liver plays an important role in the effective utilisation of protein in the horse’s body. Horses who are well cared for often take in more protein than they need. The liver is able to break down the resulting excess and non-essential amino acids. When the liver breaks down the amino acids, it removes the amino group, which is excreted as urea. The remaining carbon structure can be used as an energy source, although this is not recommended.
Synthetic function (clotting factors, proteins)
The liver is a major player in the production of almost all the major plasma proteins and low volume proteins, such as clotting factors.
Storage function (vitamins and minerals)
The liver is a vital storage organ for minerals such as iron and copper, as well as vitamins including vitamin A, D, and B12, and other proteins.
Symptoms and consequences of liver damage
In most organs, when they are damaged this usually means that cells are completely destroyed with total loss of organ function. Most, however, can repair and regenerate cells within reason. In the liver, this is a different story: when hepatocytes incur damage, the liver can generally continue to exercise most of its functions. However, this means that limited damage to liver cells is rarely noticed. One sign of early liver damage is blood protein levels dropping, but without a blood test, this goes unnoticed. Damage often only becomes visible when the hepatocytes have incurred extensive damage or are completely destroyed.
Lethargy and tiredness are tell-tale symptoms of liver damage.
The most prominent symptoms of liver damage are:
As mentioned previously, these symptoms can occur as a consequence of ragwort poisoning. Acute poisoning from ragwort is rare; more often the small but frequent ingestion of ragwort causes repeated and minor damage to the liver over a period of time. Ragwort contains a pyrrolizidine alkaloid, which passes to the liver via the hepatic portal vein. On arrival the toxin starts to damage the hepatocytes, eventually leading to shrinking and progressive fibrosis of the liver.
Nutritional guidelines for horses with liver damage
Liver failure is untreatable, but adjusting the horse’s feed can help with recovery and maintaining overall health. Always consult a vet when you have a suspicion of liver failure, and remember that prevention is the best treatment!
Easily digestible carbohydrate sources like oats are provide immediately accessible glucose and decrease the need for the liver to manufacture it. Remember that feeding soluble carbohydrates should be done with care to prevent starch overload, so frequent small feeds are recommended. Between 5-6 small feeds per day help prevent peaks and troughs in blood glucose levels. We recommend a quantity based on a proportion of 100 grams of oats, barley or maize per 100 kg of weight.
Few but high-quality proteins
Avoid ammonia build-up in your horse’s body when their liver is damaged. This can occur when the horse is fed too much protein, so limit its intake of protein-rich foods. Do make sure to supplement plenty of essential amino acids like lysine, as well as branched chain amino acids (BCAAs).
Branched amino acids increase the cell’s capacity to synthesise protein, which decreases pressure on the liver. They also help decrease tiredness and lethargy. Lastly, they decrease the chances of toxins reaching the blood-brain barrier and thereby help suppress neurological symptoms of liver damage. Because these are essential amino acids, they are not excessively taken up by the liver. Feeds such as sugar beet pulp and maize are high in BCAA’s and are therefore a good inclusion in the diet of a liver-damaged horse.
Good quality forage is essential for any horse to ensure a healthy digestive system and to satisfy the horse’s need to chew. If you can let your horse graze, this should be encouraged, as pasture is a rich source of vitamin E, which helps to support immune function. At all other times access to hay should be provided.
Horses with liver damage require forage of low to medium quality protein, but the hay must be very clean. Legume forages, such as alfalfa, should be avoided. Horses with liver damage often have poor appetites, so hay can be dampened with some diluted molasses to improve consumption. It is sometimes better to feed small hay nets on a frequent basis, rather than providing the horse with one large portion.
If your horse is prone to weight loss, consider providing an additional fibre-rich feed, such as Saracen Horse Feeds Super Fibre Cubes.
As yet, there is not much evidence regarding positive effects of certain supplements on the health of horses with liver damage. Some studies show beneficial effects from milk thistle and cider vinegar. Milk thistle contains silymarin, which protects liver cells from further damage, aids with recovery of damaged cells, and reduces inflammation. One study showed that adding 240ml of cider vinegar to the feed of a 450kg horse helped lower ammonia levels in its blood.
Milk thistle could help horses with liver damage recover.
Additional B-complex vitamins, including folic acid and vitamin K, are recommended for horses with liver damage. While a healthy liver usually processes these vitamins, an unhealthy liver may do so less successfully. Zinc supplementation may also be beneficial to horses with liver failure, as it helps process amino acid breakdown products. In humans with liver disease, zinc deficiencies have been noted to cause mental abnormalities.
Any additional supplementation of extra vitamins or minerals should be avoided unless specifically advised by your vet. Vitamins such as A, D and K are stored in the liver and can become toxic when ingested in excess. Overload of vitamin D can lead to renal failure, and excess vitamin K may cause haemolytic anaemia.
Appetite and depression
Remember that horses with liver damage may have very little appetite. In cases where the horse has an exceptionally poor appetite, it is better to offer small amounts of a feed that it will eat, rather than rigidly sticking to the rules. Horses with liver damage are prone to depression, so regular attention and stimulation are key to recovery.
A brief summary of all our tips
Remember that every horse with liver damage will display different blood levels, so make sure to consult a certified vet. If you have any questions or are looking for tailored nutritional advice for your horse with liver damage, contact nutritional expert Lizzie Drury from Saracen Horse Feeds. To get in touch, email firstname.lastname@example.org.
Text: Saracen Horse Feed